The present invention relates to a primer firing mechanism, and more particularly, to a firing mechanism for percussion primers wherein the explosive energy from a detonated explodable device is transmitted directly to the percussion primers for initiation of the percussion primers without use of an intermediary firing pin.
Commercially available percussion primers are constructed by the loading of an impact-sensitive pyrotechnic mix into a primer cup with the mix being covered by a paper disk and an anvil pressed into the cup. Normally, the primer is fired by impacting the primer cup face with a hemispherically tipped firing pin. The resulting compression of the mix between the indented cup face and the anvil causes the mix to deflagrate. This deflagration provides a flame for firing an externally disposed explodable device. The cups are made of ductile brass and copper alloys to permit deformation of the cup while maintaining structural integrity.
In the prior art, the firing of the percussion primer requires the use of an intermediary firing pin. The requirement of this intermediate firing pin for firing a primer, and particularly a percussion primer, is exemplified by U.S. Pat. Nos. 4,099,465 of Haake, 4,083,307 of Beermann et. al., 3,971,319 of Larson, 1,313,801 of Doran, and 679,792 of Stuart.
The use of a firing pin has particular disadvantages, notably comprising a moving part requiring close tolerances for firing the percussion primer. Accordingly, it is desirable to improve the reliability of the firing of percussion primers by the elimination of such moving parts. Additionally, such a reduction in the number of parts reduces fabrication, assembly, and test costs. Accordingly, it is desirable to provide a means for firing a percussion primer without the use of an intermediary firing pin.
For a primer firing mechanism it is desirable to use redundant primers within the same envelope for greater reliability. The redundancy of the primers is required to assure ignition in the event that one of the percussion primers is defective. Firing of the redundant primers using firing pins requires even more stringent tolerances and fabrication and assembly costs than that required for a single percussion primer, and additionally, presents a timing problem inasmuch as it is desirable that all of the primers be ignited at the same time. Accordingly, it is desirable to provide a means for substantially simultaneous firing of the percussion primers without using moving mechanical parts.